The invention relates to an arrangement for the transfer of plates between a plate conveyor and a storage rack or similar structure by means of a transport arm, which is arranged at the storage rack and is provided at its free end with a plate holder for engaging a plate to be transferred and which is movable between the plate conveyor and the storage structure.
The invention is particularly suitable for handling glass plates where, at the end of a glass manufacturing line, formatted flat glass plates are carried on a plate conveyor and, at the end of the plate conveyor, are taken from the conveyor and transferred to a storage rack or a similar structure. However, the application of the invention is not limited to the handling of glass plates but the arrangement according to the invention is suitable for other kinds of plates which are carried on a plate conveyor and have to be transferred from the conveyor to a storage structure or a truck or another structure. Of course, the arrangement according to the invention may also be used for the reversed procedure, that is, for the transfer from a storage structure to a plate conveyor.
During the manufacture of glass panels, a flat, continuously moving glass plate strip is formed by the deposition of a glass melt on a liquid metal bath. The flat glass strip floating on the liquid metal bath (designated therefore generally as float glass), after sufficient cooling and solidification, reaches a cutting station where the glass is cut by longitudinal and transverse cutters into smooth plates of the desired format. The cut glass plates are then transported by a conveyor to stacking locations where they are stored in stacks until they are further processed or transported elsewhere.
If the glass plates must subsequently be coated for example for providing them with certain optical properties such as light permeability, reflection behavior, optical appearance or heat radiation permeability as it is common for construction glass panels, the side of the glass to be coated must be kept free of impurities or detrimental deposits or disturbances of any type. Therefore the so-called air side of the flat glass (in contrast to the bath side, which is the side with which the glass floats during manufacture on the liquid bath), which remains free from any mechanical effects also during the transport of the glass plate on the conveyor to the stacking location since only the bath side of the glass plates is contacted by rollers of the conveyor, is selected for coating purposes.
However, during removal of the glass plates from the conveyor, the glass plates are engaged at the air sides thereof by a plurality of suction heads arranged at the end of a robotic arm and are lifted off the conveyor and transferred to the storage structure. During this procedure, impurities or tracks can be applied to the air side of the glass plates. Such tracks are normally not visible, but, upon coating of the glass surface, they may be disturbing and become visible. With automotive or building glass panels then a ring pattern may form at the suction head engagement locations of the glass panels when they are fogging up, which is very undesirable.
EP 1 298 080 A1 (U.S. Pat. No. 6,659,265) discloses an apparatus for the transfer of plates from a plate transport device to a storage rack which attends to the same problem. There, a robot arm, which is arranged at a plate transfer location, has at its free end a suction from which can be pivoted selectively into a vertically upward oriented position and which can be introduced into open areas in the plate conveyor in order to engage a glass plate on the plate conveyor at the bottom side thereof for moving it to the storage rack. However, the suction frame can also be pivoted into a downwardly oriented position for engaging the plates at the air sides thereof where this is of no importance for the further use of the glass plates. With this arrangement, a motor drive is required for pivoting the suction frame into the respective desired position. The motor drive with the respective means for the accurate positioning of the suction frame in the respective pivot position involves an expensive design and service requirements and makes the apparatus more prone to failures.
It is therefore the object of the present invention to provide an arrangement for the transfer of plates, particularly glass plates, from a plate conveyor to a storage rack or similar structure which permits the engagement of the plates from the bottom sides thereof, namely the bath side of glass plates, and which does not require a motor operated pivoting mechanism between the robot arm and the suction frame.